Did you say what source material you were seeing the shadow detail problem with ?
I had wondered if you were using a ub900 from a 4k disc, in which case the recent Panasonic patches to allow hdr to be re-mapped for different ambiant light settings might have been the solution
I have no idea what any of that means ... I was using files downloaded from http://demo-uhd3d.com/categorie.php?tag=hdr.
On the new one I got today I have no shadow issues at all. It's a lot better for some reason... ?